ES2988332T3 - Prosthetic valve crimping device - Google Patents

Abstract

An apparatus for crimping expandable prosthetic heart valves, the apparatus comprising jaws having linear movement toward a center, a stationary base including guide slots oriented toward the center, and a rotatable mechanical member rotating about the center, the member including a spiral track, and three removable attachments consisting of: a handle level stop member 108 removably attached to the valve crimping device within an opening formed in the housing 2, the handle stop member 108 calibrated to stop movement of the handle 5 when the proper opening size for a particular crimping operation is reached; a crimping valve gauge 112 removably mounted on the base 4 and providing a tube 116 having a tapered through hole with a minimum diameter that is equal to the minimum opening diameter limited by the stop member 108; and a balloon gauge removably mounted on base 4 having an internal diameter calibrated to the maximum desired size of the expandable balloon used to place the prosthetic valve. (Automatic translation with Google Translate, no legal value)

Description

DESCRIPTION

Prosthetic valve crimping device

Background of the invention

Field of invention

The present invention relates to a crimping device, and more particularly, to a crimping system for crimping an endoprosthetic valve, such as a heart valve, from a large diameter to a smaller diameter.

Description of the related technique

A stent is a generally cylindrical prosthesis introduced into a lumen of a body vessel by means of a catheterization technique. Stents may be self-expanding or balloon-expandable. Balloon-expandable stents are typically crimped from a large initial diameter to a smaller diameter prior to advancement to a treatment site in the body. Prior to crimping, a balloon-expandable stent is typically placed over an expandable balloon on a catheter shaft. In cases where the stent was manufactured with its diameter fully crimped, the stent is expanded and then crimped over the balloon. To ensure safety, the crimping procedure must be performed in a sterile environment. Over the years, attempts have been made to crimp the stent into a balloon intraoperatively in the sterile field. However, most stents are now “pre-crimped” into a suitable balloon at the factory and then delivered to the physician ready for use.

An example of a shirring device based on moving segments is disclosed in US Patent No. 6,360,577 to Austin. This shirring device uses inclined planes that force jaws to move from the open position to the closed position. In a major deficiency associated with this type of device, the length of the inclined plane is given by a full circle divided by the number of activated jaws. The more shirring jaws there are, the shorter the inclined plane for activation. The drawback of this method is the contradiction created by the equation of 360 degrees divided by the number of jaws. In order to achieve a uniform opening for shirring the valve, a large number of jaws is needed, but a long inclined plane is preferable to reduce circumferential resistance or friction forces. For example, a linear movement of 7 mm is achieved by a rotational movement of approximately 45 degrees (360 divided by 8 jaws), which is a fairly steep angle of inclination that requires more turning force to overcome. The effectiveness of this type of device is therefore substantially limited.

In recent years, a variety of prosthetic valves have been developed in which a valve structure is mounted on a stent and then delivered to a treatment site via a percutaneous catheterization technique. Prosthetic valves are typically much larger in diameter relative to coronary stents. For example, a typical coronary stent diameter is only 1.5 to 4.0 mm at its expanded size, whereas a stented prosthetic valve diameter will typically be in the range of approximately 19 to 29 mm, at least 5 times larger than a coronary stent. In another difference, coronary stents are stand-alone devices whereas in prosthetic valves, the stent functions as a support structure to hold the valve structure. The valve structure is typically composed of biological materials, such as pericardial valves or harvested valves. For improved function after deployment, it is often desirable to preserve such valves in an open (i.e., expanded) diameter within a preservation solution. Using this procedure may be necessary to crimp the valve in the operating room a few minutes prior to implantation, thereby preventing the manufacturer from pre-crimping a balloon.

Due to the unique shirring requirements for stent-based prosthetic valves, existing shirring devices configured for use with coronary stents have been found to be unsuitable for use with stent-based prosthetic valves. Furthermore, as discussed above, existing shirring mechanisms suffer from a variety of shortcomings that limit their ability to be adapted for use with stent-based prosthetic valves. Due to the shortcomings associated with existing shirring technology, Percutaneous Valve Technologies, Inc. (PVT) developed a new shirring device that is more suitable for use with stent-based prosthetic valves. This crimping device is described in US Patent No. 6,730,118 <commonly assigned to Spenser> et al. <and relates to a crimping device that is adapted to crimp a> prosthetic valve as part of the implantation procedure.

Another version of a prosthetic heart valve crimper is marketed by Machine Solutions Inc. of Flagstaff, Arizona. The HV200 is a disposable crimper that uses multiple pivoting segments to crimp transcatheter heart valves. Machine Solutions crimpers are also disclosed in U.S. Patent Nos. 6,629,350 and 6,925,847, both issued to Motsenbocker. These crimpers rely on segments that rotate about pivot pins to create radial compression. Unfortunately, the pivoting design tends to concentrate stress in certain areas of the individual segments and the mechanism for pivoting them. In addition, the user must apply significant force to close the crimper opening around a relatively large transcatheter heart valve.

US 2004/0128818 A1 discloses, inter alia, a hand-operated apparatus for crimping a stent by segmental radial compression. The apparatus includes a stationary housing; a rotatable drive hub, movable relative to the housing; a crimping head coupled in communication with the housing and the drive hub; and an actuator handle connected to the housing and the drive hub. The crimping head includes a plurality of segments oriented about a central opening that receives a stent to be compressed. The segments each have a proximal end and an angled distal end with at least one angled side face terminating in an edge of a predetermined length and defining the central opening. Activation of the handle rotates the drive hub, causing the segments to move and pivot, resulting in closure of the central opening and compression of the stent.

Although the heart valve crimping technology available to date provides an improvement over existing stent crimper technology, it has been found that there is still a need for a more effective device. It is desirable that such a device be able to crimp a valve from a diameter of about 29 mm to a crimped size of about 6 mm without requiring excessive force and without inducing high mechanical stresses within the device. It is also desirable that such a device be simple to use and relatively inexpensive to manufacture. It is also desirable that such a device be sterile and suitable for manual operation in a catheter laboratory or operating room. The present invention addresses this need.

Summary of the invention

The present invention provides a system for crimping expandable prosthetic heart valves as defined in claim 1 and an assembly defined in claim 15 comprising the crimping system of claim 1. Additional possible advantageous configurations can be found in claims 2 to 14.

The present invention is particularly well suited for use with stented prosthetic heart valves, such as a prosthetic aortic valve.

One aspect of the present invention is the introduction of an improved shirring device, based on jaws with a linear movement towards a center, a stationary base including guiding grooves oriented towards the center, and a rotating mechanical element rotating about the center, the element including a spiral track.

In a preferred embodiment, the jaws are activated by the rotating mechanical element. The forces applied to the movable jaws are predominantly in the radial direction. When shirring a stent-based valve symmetrically, thereby reducing its diameter (as opposed to crushing and flattening), the radial forces are efficient and effective in uniformly reducing the circumference of the prosthetic valve. Accordingly, the force applied to the jaws by the surgeon through an additional mechanical element is in the same vector and opposite to the reaction force of the stents while they are being shirred. This advantageously provides maximum efficiency to the shirring process.

Another preferred aspect is the use of a rotating plate that includes a spiral track used as a mechanical element, which transfers the surgeon's force to the jaws. The gradually inclined spiral track, in this case 225 degrees, reduces the resistance to the shirring operation so that approximately 5 times less force is required by the surgeon than in previous designs.

Another aspect is that the guide grooves, in addition to the above-described spiral activation track, ensure that the jaws move in a linear manner. In the present invention, each jaw has two guide grooves, one main groove in the centre of the line of application of force/reaction, and the other one parallel to the main groove.

Another aspect is the design of the spiral in a way that allows more than one thread to be used to activate the jaws, the benefit of this feature being both the ability to build a reasonably sized gatherer and the cost of gathering the gatherer to be reduced.

Another aspect is the ability to activate the jaws symmetrically from both sides of the jaw, while leaving the middle section of the jaw free.

Another aspect is a novel design that allows for activation of the jaws at more than one contact point, allowing for application of a smaller force to each contact point, resulting in the possibility of making the part from relatively inexpensive plastic materials, which helps to reduce the overall price of the product. Making the device inexpensively allows for the device to be disposable, which is an important aspect of the invention.

Another aspect is the arrangement of the jaws from the aspect of their angles. As the jaws move into these guide grooves and are activated by the spirals, the surgeons' force is transferred to the jaw through the contact points. The selected number of jaws with a constant distance ratio between the jaws dictates a certain spiral angle.

Another aspect of the crimping mechanism is a stop mechanism that prevents the surgeon from accidentally crimping the device excessively.

In another embodiment, a shirring mechanism includes a rotational element activated by a rotating handle and a pinion gear that allows the element to be rotated more than 360 degrees. The rotating element is activated by a lever handle and the stationary part is connected to a base. This configuration is advantageous for several reasons. For example, the arrangement allows for a larger transmission ratio, and eliminates lateral forces throughout the apparatus resulting from manual forces applied by the user, which tend to move the apparatus on the table. If the shirring mechanism is activated by two rotating elements on both sides of the jaws, both elements are connected by a bridge, which will restrict the possible movement of the handle to less than 360 degrees.

A preferred aspect is a prosthetic valve crimping device that can reduce the diameter of an expandable prosthetic valve having a support frame by at least 10 mm. For example, prosthetic heart valves expand to about 29 mm, and can be crimped with the device of the present invention to about 6 mm, which is a reduction of 26 mm. The device comprises a base and a housing fixedly mounted thereon, the housing defining a central axis and having at least six evenly spaced spoke-like guide channels, each of the guide channels having a length of at least 5 mm. A plurality of circumferentially disposed nesting jaws are axially and rotationally constrained but radially movable within the housing. Each jaw has a cam element extending axially toward a guide channel, the number of jaws being equal to the number of guide channels, each jaw being substantially radially oriented and being formed in one piece. Each jaw defines an inner end having a partial crimping surface which mates with the same on the other jaws to form a crimping opening of varying diameter, and which has an axial dimension sufficient to crimp an expandable prosthetic valve. Each partial crimping surface terminates on one side at a point which is constrained to move along a radial line when the jaw moves along the guide channel. A cam plate rotates about the housing and has a plurality of cams, at least one for each jaw, which act directly on the cam elements and move the jaws without any intermediate connecting elements. A manual actuator rotates the cam plate and simultaneously moves the jaws inward to reduce the diameter of the opening by at least 10 mm to crimp an expandable prosthetic valve placed within the opening, and subsequently outward to release the valve after crimping.

Desirably, each jaw includes a linear slider that fits within the guide channel, and the guide channels are oriented along radial lines from the central axis. The cam element in each jaw may be positioned along a radial line from the central axis and extend through a guide channel in the housing, the jaw further including a linear flange parallel to, but offset from, the radial line that fits within a secondary guide channel in the housing. Each jaw preferably comprises an outer head portion from which the cam element extends and an inner generally circumferentially oriented finger with a recess defined therebetween, and wherein each jaw nests within the recess of an adjacent jaw and the partial shirring surface is defined on the radially innermost face of the finger. In one embodiment, the housing flanks the jaws and defines guide channels on both axial sides thereof, and each jaw includes at least one cam element extending on each axial side to engage a guide channel. Each jaw may have two cam elements extending axially from at least one side, wherein the cam plate includes cams engaging each of the two cam elements. The cams and the cam plate may be spiral tracks that act to move each of the cam elements radially inwardly. Preferably, each cam plate includes a plurality of superimposed spiral tracks, and each jaw includes two cam elements extending axially from at least one side toward different spiral tracks. Each of the spiral tracks preferably extends angularly at least 360°.

Another aspect of the invention is a prosthetic valve crimping device capable of reducing the diameter of an expandable prosthetic valve having a support frame. The device includes a housing defining a central axis and having at least six evenly spaced spoke-like guiding channels.

A plurality of circumferentially arranged jaws are axially and rotatably constrained but radially movable within the housing. Each jaw has a cam element extending into a guide channel, the number of jaws being equal to the number of guide channels. Each jaw is substantially radially oriented and is formed in one piece having an outer end and an inner end. Each inner jaw end has a partial crimping surface which combines with the same on the other jaws to form a crimping opening of varying diameter and having an axial dimension sufficient to crimp an expandable prosthetic valve. A cam plate rotates about the housing and has a plurality of spiral cams which act directly on the cam elements and move the jaws without any intermediate connecting elements. The spiral cams extend about the axis at an angle of at least 60° to provide a mechanical advantage sufficient to crimp expandable prosthetic valves. A manual actuator rotates the cam plate and simultaneously moves the jaws inward to crimp an expandable prosthetic valve placed within the opening, and then outward to release the valve after crimping.

In a still advantageous aspect of the invention, a disposable and portable crimping system for prosthetic valves is provided. The system includes a base and a valve crimper mounted on the base, having a housing and a plurality of jaws radially movable within the housing. Each jaw defines an inner end having a partial crimping surface that combines with the same on the other jaws to form a crimping opening of varying diameter. Each jaw has an axial dimension sufficient to crimp an expandable prosthetic valve. A stop-limited actuator simultaneously moves the jaws inwardly to reduce the diameter of the opening by at least 10 mm to crimp an expandable prosthetic valve positioned within the opening, and subsequently outwardly to release the valve after crimping. The system further features a support frame gauge mounted on the base having a crescent-shaped through-hole with a minimum diameter that is equal to the minimum opening diameter as limited by the stop. Finally, a base-mounted balloon sizer features a through hole with a diameter sized to size an expanded balloon therein to a maximum diameter sufficient to expand a prosthetic valve.

The system further includes a stop element removably attached to the valve shirr, wherein the support frame gauge and the balloon gauge are removably mounted to the base. The movable stop element, the support frame gauge and the balloon gauge may be formed in the same color, other than the color of the valve shirring device. Preferably, each jaw has a partial shirring surface defined at an inner end and terminating at a point lying on a radius, the combination of all partial shirring surfaces defining the opening, and wherein each jaw moves linearly along a line, the point remaining on the radius and the partial shirring surface not rotating. Furthermore, each jaw may comprise an outer head portion and a generally circumferentially oriented inner finger with a recess defined therebetween, wherein each jaw nests within the recess of an adjacent jaw and the partial shirring surface is defined on a radially innermost face of the finger.

Another aspect of the present disclosure involves a method of selecting and using a kit to prepare a prosthetic valve for use. The kit preferably includes a crimping mechanism and accessories such as, for example, a handle lever stop element, a balloon sizer, and/or a crimped valve sizer. Each of the accessories is preferably removably attachable to the crimping mechanism. The stop element provides a physical stop.

The crimping device is preferably mounted adjacent to the crimping mechanism. Once the prosthetic valve is crimped, the prosthetic valve is placed into the sizer to verify that its outer diameter is at the desired level. The balloon sizer provides a ring that has an inner diameter calibrated to the maximum desired size of the expanded balloon used to deliver the prosthetic valve. The balloon sizer allows the surgeon to determine the amount of saline required to expand the balloon for proper development of the prosthetic valve in the patient.

Brief description of the drawings

Figure 1 is a perspective view illustrating a preferred embodiment of an improved shirring mechanism.

Figure 2 is an exploded perspective view showing the components of the shirring mechanism.

Figure 3 is a side view illustrating the cooperation of the components.

Figure 4 is a side view illustrating the spiral track configured to move the jaws.

Figure 5 is a side view illustrating the jaws in the closed position.

Figure 6 is an enlarged view illustrating a portion of the jaws.

Figure 7 illustrates a first cover formed with a spiral track.

Figure 8 is another exploded view illustrating the main components of the shirring mechanism.

Figure 9 illustrates a single jaw configured for use with the shirring mechanism.

Figure 10a illustrates the interaction between two adjacent jaws.

Figure 10b is a side view illustrating the profile of a preferred jaw.

Figure 10c is a side view illustrating an alternative jaw tip.

Figures 11a and 11b are additional exploded views of a system not forming part of the invention.

Figure 12 is a perspective view illustrating a preferred embodiment of a crimping mechanism of the present invention together with a unique removable accessory assembly for a particular valve size.

Figure 13 is an exploded view of the accessories of Figure 12.

Figure 14 is a perspective view of an exemplary prosthetic heart valve having an expandable support frame and a plurality of flexible leaflets therein.

Figure 15 is a side view of the prosthetic heart valve of Figure 14 crimped to a reduced diameter around a balloon catheter.

Detailed description of the preferred embodiments

The present invention provides an improved crimping device for stents or prosthetic valves. Particularly advantageous features of the present crimping device allow for reduction in diameter of relatively large stents or prosthetic valves. The crimping device is particularly suited for crimping prosthetic heart valves that have significantly larger expanded diameters than the majority of stents currently in use. According to Chessa, et al., Palmaz-Genesis XD stents (Cordis, J&J Interventional Systems Co.) are designed for an expansion range of 10 - 18 mm and are considered large or extra-large stents (see, Results and Mid-long-term Follow-up of Stent Implantation for Native and Recurrent Coarctation of the Aorta, European Heart Journal, Volume 26, No. 24, pp. 2728 -2732, published online September 26, 2005). The most commonly used stents are significantly smaller, in the 3 - 6 mm range. The stent gatherers for these stents have been shown to be inadequate for downsizing even the largest prosthetic valves, such as stented prosthetic heart valves. Furthermore, aspects of the present shirr may also be applicable for use in shirring stents, although certain features described herein make it particularly well suited for shirring large diameter stents, coated stents, and prosthetic valves.

The term “stented valve” as used herein refers to prosthetic valves for implants, primarily prosthetic heart valves, but also conceivably venous valves and the like. A stented valve has a support frame or stent that provides primary structural support in its expanded state. Such support frames are typically tubular when expanded, and may expand using a balloon or due to their own inherent elasticity (i.e., self-expanding). An exemplary stented valve is illustrated with respect to Figures 14 and 15, although the present invention may be useful for crimping other such prosthetic valves.

Referring now to Figure 1, a preferred embodiment of an improved prosthetic heart valve crimping mechanism is shown. The crimping mechanism is formed by twelve jaws 1 disposed about axis 10. The jaws are shown in a semi-closed position defining an opening of variable size between their inner ends. The crimping mechanism has a stationary portion comprising a split or two-part housing 2 and a base 4. The stationary portion supports first and second rotational elements or plates 3 which are rotated about a central axis 10 by an actuator or lever handle 5.

Referring now to Figure 2, an exploded view of the shirring mechanism is provided. From this view, it can be seen that the jaws 1 are arranged around the central axis 10 and that the two housing parts 2 flank the jaws on either side. Each housing part 2 comprises a generally disk-like shape with a radially oriented circular wall and an outer rim extending towards the opposite housing part. The outer edges of both housing parts 2 contact each other and surround the jaws circumferentially. The assembly of the housing parts 2 thus defines within them a generally cylindrical cavity which constrains the jaws 1, however, the axial dimension of the jaws 1 is such that they are held between the inner faces of the two circular walls of the housing parts 2 with sufficient clearance to allow sliding movement therein. As will be shown and described below, the number of housing parts is to rotationally restrict each of the jaws 1 to allow only radial movement.

As seen in Figure 2 and in detail in Figure 9, each jaw 1 is preferably provided with a pair of outwardly directed guide sliders 17 on both axial sides near the radially outermost extension of the jaw. The guide sliders 17 extend through and interact within guide slots 15 in each stationary housing portion 2 to restrict the jaws to linear sliding movement toward and away from the central axis 10. Secondary elongated guide tabs 18 extend from both sides of each jaw 18 in engagement with parallel secondary slots 16 located in each stationary housing portion 2. The four guide sliders 17 and the guide tabs 18 on each individual jaw are parallel, as are the four corresponding slots 15, 16. The resulting assembly restricts the movement of the jaws 1 within the housing 2 to follow the slots 15, 16, which are generally oriented radially. In fact, the radius-type slots 15 lie on radial lines outward from the center of the shirring mechanism, while the secondary slots 16 are parallel to, but slightly spaced from, them.

Rotation of the first and second outer rotational plates 3 causes translation of the jaws 1 and thereby crimps the valve. Both plates 3 are pivoted to rotate on the adjacent housing portion 2 about the axis 10. The handle 5 is attached via a clamping arrangement to both plates 3 to rotate them in tandem. Cuts, grooves or spiral tracks 14 are provided in each rotational plate 3 on each side of the crimping mechanism to translate the rotational motion of the lever handle 5 into a linear motion of the jaws 1. The spiral tracks 14 are desirably formed between spiral walls extending inwardly from the rotational plates 3. The spiral tracks 14 interact with trip pin-shaped cam elements 11 located on both sides of each jaw, particularly extending outwardly from each guide slider 17.

Referring again to Figure 4, a section of the shirring mechanism is illustrated through the rotational plate 3 so that the co-operation with the driving cam elements 11 can be observed. Upon rotation of the outer plates 3 (clockwise in this view), the spiral tracks 14a, 14b and 14c apply a generally radially inward cam force, shown by arrows 41, to the driving cam elements 11. Lines 42 illustrate instantaneous tangents to the spiral track 14, which is approximately perpendicular to the direction of movement (i.e., toward the central axis 10) of the jaws and driving cam elements 11.

Geometrical constraints cause movement of the actuating cam elements 11, and hence of the jaws 1, towards the central axis 10. Furthermore, movement of the jaws is restricted by the joint action of the guiding slots 15, 16 and the sliding elements 17 and the tabs 18 and by the geometry of the jaw itself, which will be discussed further with reference to Figures 9 and 10. When the lever handle 5 is rotated in the direction of arrow 43 in Figure 4, the rotational plates 3 rotate, thereby causing the spiral tracks 14 to rotate. This rotational movement of the spiral tracks pushes the jaws inwards, thereby closing the opening 50 (Figure 5). Movement of the jaws 1 towards the centre causes the stent-containing valve 20 to crumple. Figure 4 and Figure 7 show one of the rotation plates 3 in isolation and better illustrate the shape and distributions of the three independent spiral tracks 14a, b and c, which geometrically fit into the three sets of four jaws described in Figure 3.

Referring now to Figures 3 and 4, a cross-sectional view of the shirring mechanism is provided, in which the jaws 1 are shown in a partially open position. As discussed above, the twelve jaws 1 are arranged in a circular configuration about the central axis 10. The lines of jaw movement for two jaws are shown by the dashed lines 30, and their respective directions of gathering movement by the arrows 31. The linear guide sliders 17 and tabs 18 are also shown here positioned relative to the guide slots 15 and 16. Three sets of jaws numbered 1 through 4 are illustrated. The difference between the jaw positions relates to the placement of the cam elements (see 11a through 11d), two of which on each side of each jaw 1 are held within the spiral track 14 on the rotational plates (see item 3 in Fig. 2). In the exemplary embodiment, therefore, there are four cam elements 11 on which four spiral tracks 14 act for each jaw 1.

In this example, there are three independent spiral tracks 14a, 14b, 14c formed on each rotational plate 3. Each spiral track 14 extends from a point near the outer periphery of plate 3 and terminates inwardly therefrom at a radial location identical to the termination points of the other tracks. The pitch of the tracks is constant and the three tracks are symmetrically cut, so a constant distance between the cam elements creates a geometric match to the tracks, even though each cam element is actuated by a different track. The respective start and termination points of the tracks 14 are evenly spaced circumferentially, in this case 120° apart. Each spiral track 14 extends more than 360°, preferably about 450°, about the axis 10. This relatively shallow spiral helps to reduce the amount of force required to rotate the lever handle 5 because the tracks contact and apply radial forces primarily to the cam elements. Stated another way, the increased angle of the spiral tracks 14 makes the mechanism more difficult to operate since the angled spirals apply a larger circular or frictional force component to the contact points of the cam elements.

Figure 5 is a view similar to Figure 4 but with the lever handle 5 fully rotated toward a stop element 6 which prevents further rotation. The jaw opening 50 is closed to the extent necessary to fully crimp the stented valve 20a. It is noted that the dual actuating cam elements 11, for each jaw 1, engage different spiral tracks 14, but more radially inward of the spirals. For example, cam element 11c engages track 14a and cam element 11d engages track 14.

There are a total of twelve jaws grouped into three identical sets of four jaws as indicated in Figure 3. Figure 4 illustrates in cross section the evenly circumferentially spaced sets of two cam elements 11 on one side of each jaw 1. The two cam elements 11 on each side of each jaw 1 protrude into different spiral tracks 14. Additionally, due to the nature of the spiral tracks 14 and space limitations, the cam elements 11 of adjacent jaws are slightly radially offset from each other. For example, in Figure 4, the spiral track 14c terminates near the 3:00 o'clock position with a middle portion of the spiral track 14b radially inward immediately therefrom. One of the two cam elements 11 in a jaw 1 oriented precisely at the 3 o'clock position engages the outer race 14c while the other engages the adjacent race 14b. Looking counterclockwise, the two cam elements 11 in a jaw 1 oriented at the 2 o'clock position also engage these two races 14b, 14c, which have now spiraled inwards a short distance. Continuing counterclockwise further, the jaws 1 at the 1 o'clock and 12 o'clock positions have cam elements 11 which are located even further radially inwards along the same two spiral races 14b, 14c. At 11 o'clock, one of the cam elements 11 engages the spiral race 14a while the other engages the spiral race 14C. This pattern continues for each set of four jaws 1.

Providing two independent cam elements 11 on each jaw 1 reduces the force applied to each cam element, ideally dividing the force in half. Manufacturing tolerances may cause one of the two spiral tracks to contact one of the cam elements before the other pair, but ultimately both cam elements are acted upon. In addition, each jaw 1 desirably features a pair of cam elements 11 extending from both sides, which are acted upon by spiral tracks 14 on two of the rotating plates 3. Because the cam forces are applied on both sides of each of the jaws 1, there is symmetry in the stresses and less chance of binding and wear from misalignment.

Working prototypes have been made with 6 jaws, although 6 is considered to be the minimum. The number of jaws desirably ranges from 8-12. The fewer the jaws, the larger each jaw will need to be to provide the necessary contributing gathering surface in the opening. Also, decreasing the number of jaws affects the circularity of the opening (more jaws result in a more perfect circle). On the other hand, including more jaws reduces the size of each jaw and increases the complexity of the fixtures. Ultimately, considerations of material strength and cost limit the number of jaws.

Referring to Figure 6, an enlarged view of the jaws 1 is provided in which the direction of movement 30 of the jaw identified as jaw No. 2 towards the central axis 10 can be observed. The sliding guide elements 17 and the tabs 18 and the guide grooves 15, 16 are again clearly seen. Line 62 illustrates a line of geometric symmetry of the jaw opening 65, which preferably remains constantly perpendicular to the line of movement 61 of the jaw identified as jaw No. 1, which extends through the center of the activation cam elements 11.

Referring to Figure 8, another exploded view of the shirring mechanism shows the two rotating plates 3 on either side of the jaws 1 with the housing portions 2 removed. The spiral tracks 14 receive the cam elements 11R and 11L located on opposite sides of the jaw identified as jaw No. 1, while allowing an axially central portion of the jaw 81 to remain free. This arrangement reduces the stress on each of the four pins located on each jaw. The device so arranged operates symmetrically and the danger of self-locking that could occur when a jaw is activated from only one side is substantially reduced. In other words, activation of the jaw from two sides creates a balanced net radial force on the jaw with no moment (torque) that might otherwise lead to binding.

Referring to Figure 9, it can be seen that one of the jaws comprises the guide sliders 17 and tabs 18 (on both sides) and the four cam elements 11L and 11R. The radially inner end of each jaw defines a wedge-shaped finger 52 defined by axially oriented faces disposed in planes within which lines 55 and 56 lie. A portion of the radially inner face of each jaw 1 forms a portion of the opening 50 and is 1/12 of the total opening in this example. Each jaw 1 includes a relatively enlarged head portion 57. A cutout or recess 58 narrows the material between the head portion 57 and the finger 52 to a bridge 59.

Referring to Figures 6 and 10a, the nesting relationship between the series of circumferentially spaced jaws 1 is shown. This geometric nesting of the jaws provides specific benefits including excellent mechanical leverage between the lever handle 5 and the crimping force applied to the stented valve, reduced device complexity, and reduced stresses on each jaw. First, a more complete understanding of the jaw geometry is necessary.

Referring to Figures 10a and 10b, the geometric relationship between the jaws is illustrated. Line 61 illustrates the line of motion of the illustrated jaw, which has a certain angle a between it and the other jaws. <Because there are 12 jaws and the device is symmetrical, the angle> a< will be 30 degrees. For each jaw 1,> the geometric symmetry line 62 is perpendicular to the line of motion 61 and bisects the angle formed by adjacent jaw tip lines 55 protruding along the radially inner faces thereof. The radially inner jaw faces extending along the tip lines 55 in turn form the perimeter of the opening 50 for closing the stent when crimped. Line 56 on the radially outer face of each wedge-shaped finger 52 is a mirror image line of line 55 (about line 62). The geometric constraint is that the outer face of each finger 52 extending along line 55 slides over the inner face of the finger 52 of the adjacent jaw extending along line 56 when closing or opening the jaws in the direction of the lines of motion 61.

Point 100 is the intersection of lines 61, 62, 55 and 56 and is a geometric position fixed to a jaw, and moves with it when the jaw moves. Point 101 is the intersection of the movement direction lines 61 for the twelve jaws 1. Point 101 corresponds to the axial center 10 of the shirring mechanism and is always constant with respect to all moving and stationary parts of the shirring mechanism. As shown in Figure 10c, it is also possible to add a radius 102 to the jaw tip, which will be selected according to the minimum shirring size.

Figure 10b shows a top view of a clamp. The angle p included between lines 55 and 56 is always identical to the angle a shown in Figure 10a and is determined by the number of clamps in the shirring mechanism, for example twelve clamps will result in 30 degrees, while six clamps will result in 60 degrees.

Referring again to Figure 3, the lines of force 30, 31 applied to the jaws are derived from contact between the spiral tracks 14 and the cam elements 11. The lines of force extend directly radially inward, and are such that the cam elements 11 for each jaw lie on a radial line from the center. Figure 10b shows that the radial line extends through the intersection point 100, which is the apex of the wedge-shaped finger 52. Figure 10a illustrates the radially inner end of the jaw “2” nesting in the recess 58 in the jaw “1” such that the fingers 52 overlap in the opening. In fact, the entire surface area of the outer face of the finger 52 of the jaw “2” that contributes to the opening is included within the angle a. Again, because there are 12 jaws, the angle a<will be 30 degrees (360°/12). Because the outer faces of the fingers 52 are straight, the opening actually describes a dodecagon. It will therefore be seen that reducing the number of jaws gradually reduces the number of straight sides of the polygon described by the opening 50.

This nested jaw arrangement facilitates the application of a direct radially inward force on each jaw and on each jaw surface contributing to the opening. It is important to note that the outer head portions 57 of the jaws 1 are spaced apart and can therefore be acted upon along different radial lines, but the inner ends nest together with wedge- or ramp-shaped fingers which have engaging surfaces that permit relative sliding while maintaining contact with each other. Furthermore, although the wedge-shaped fingers 52 are cantilevered by the cutout portion 58 of the jaw, the stresses therein are made more uniform by the gradually widening cross section toward the connecting bridge 59. The radially inward forces applied to the cam elements 11 travel through the head portion 57, the bridge 59, and along the fingers 52. It should be noted that the circumferential width of each jaw 1 is substantially the same from its outer end to its inner end. This unique arrangement allows for nesting of the inner ends of the jaws and allows for direct radial application of the crimping force to the prosthetic valve.

Figures 11a and 11b illustrate an alternative rotational plate 3, which does not form part of the invention. Instead of using a lever handle 5 (as discussed above with reference to Figure 1), the actuator comprises a rotatable handle 95 connected to a shaft 96 and a pinion gear 97 for rotation of a single rotational plate 3. The pinion gear 97 meshes with the gear 98 on the rotational plate. Activation cam elements 11 on a single side of the jaw engage the single spiral track 14 and are guided by the engagement of guide slots 15 and 16 to guide sliders 17 and tabs 18. In this example, there are only six jaws 1. Since there is a mechanical advantage provided by the gear arrangement which reduces the activation force required, activation of the jaws on only one side is possible. Also, there is no need for more than one spiral track as there are only six jaws.

Figures 12 and 13 illustrate an advantageous aspect of the present invention that greatly reduces manufacturing costs. Figure 12 illustrates a prosthetic valve ruffler system 104 that includes the ruffle mechanism 106 described above and three removable accessories seen exploded in Figure 13. Specifically, the removable accessories include a handle lever stop member 108, a balloon sizer 110, and a ruffle valve sizer 112. Each of these accessories 108, 110, 112 is removably attached to the aforementioned ruffle mechanism, with the stop member 108 fitting closely within an opening formed in the housing 2 and the sizes 110, 112 desirably being mounted somewhere on a base 114 of the ruffle mechanism.

The stop element 108 is previously shown at 6 in Figure 1 and provides a physical stop to the rotation of the lever handle 5 in the direction of a reduced shirring opening. That is, when the shirring mechanism 106 is operated with an expanded prosthetic valve therein, the lever handle 5 rotates in one direction until its movement is prevented by the stop element 108. The size of the stop element 108 is calibrated to stop the movement of the lever handle 5 when the appropriate opening size for a particular shirring operation is reached. That is, prosthetic valves having various expanded diameters are crimped by different amounts, necessitating different magnitudes of rotation of the lever handle 5. By forming the stop element 108 separable from the crimping mechanism 106, the same crimping mechanism can be used for valves of different sizes by simply selecting the appropriate stop element 108 from a set of differently sized stop elements.

A shirred valve sizer 112 provides a convenient check of the success of the shirring operation. The sizer 112 is mounted directly next to the shirring mechanism 106 and, after a prosthetic valve has been so restricted, is placed within the sizer 112 to verify that its outer diameter is as expected. If for some reason the shirring mechanism 106 operates or the prosthetic valve pops out after being compressed inward, the valve may be too large to pass through the available delivery catheter or cannula. The shirred valve sizer 112 provides a tube 116 having a tapered through hole with a minimum diameter that is equal to the minimum opening diameter limited by the stop element 108. The shirred prosthetic valve will typically be mounted on a balloon catheter that is used to pass the prosthetic valve through the sizer 112 after it has been shirred. Any inadequacy in the crimping process is then corrected by compression of the prosthetic valves as it passes through the tapered through-hole of tube 116.

Finally, the balloon sizer 110 provides a ring 118 having an inner diameter calibrated to the desired maximum size of the expanded balloon used to deliver the prosthetic valve (if the prosthetic valve is balloon expandable). Prior to crimping the prosthetic valve around the balloon, the surgeon expands the balloon within the ring 118. Expansion of such balloons is typically accomplished by injecting a saline solution into the balloon catheter to fill the balloon. Once the balloon is filled so that it expands to its limit within the ring 118, the exact amount of saline solution needed for expansion is known. By removing the saline solution from the balloon and maintaining it in the same syringe that will be used to deliver the prosthetic valve, the physician ensures that the balloon will re-expand to its desired limit.

The prosthetic valve crimping system 104 described above is extremely convenient and flexible. For the physician, the system provides in one hand-held device all the tools necessary to calibrate the delivery balloon, crimp the prosthetic valve around the balloon, and ensure that the crimped diameter is accurate. Desirably, the system is constructed primarily of molded plastic parts that are lightweight and also relatively inexpensive to manufacture. Thus, the cost of the device, which is discarded after each use, is reduced. For the manufacturer, it is only necessary to produce one crimping mechanism 104 along with different sized accessory sets 108, 110, 112.

To make the system even easier to use, each set of three fittings 108, 110, 112 is desirably a different color than the other sets. Thus, the three fittings for a 25 mm (expanded diameter) prosthetic valve may be green, while the three fittings for a 29 mm prosthetic valve may be red. This not only makes assembly of the system easier, but also provides a level of confidence to the physician that the proper fittings have been supplied.

14 illustrates an exemplary balloon-expandable prosthetic heart valve 120 having an inflow end 122 and an outflow end 124. The valve includes an outer stent or support frame 126 supporting a plurality of flexible leaflets 128 therein. 14 shows the valve 120 in its expanded or operative form, wherein the support frame 126 generally defines a tube having a diameter Dmax, and three leaflets 128 are attached thereto and extend into the cylindrical space defined therein to coapt against one another. In the exemplary valve 120, three separate leaflets 128 are each attached to the support frame 126 and to the other two leaflets along their lines of juxtaposition, or commissures. Of course, a complete bioprosthetic valve such as a porcine valve could also be used. In this sense, “leaflets” means independent leaflets or leaflets within a complete xenograft valve.

Additional details on exemplary prosthetic heart valves of a similar type can be found in U.S. Patent No. 6,730,118. In addition, the Cribier-Edwards™ percutaneous aortic heart valve available from Edwards Lifesciences of Irvine, CA is another balloon-expandable prosthetic heart valve of a similar nature.

Figure 15 shows the valve 120 mounted on a balloon 130 prior to inflation. The crimped outer diameter of the valve 120 is indicated by Dmin. The balloon 130 is typically mounted on the end of a catheter 132 which is guided to the implant sites on a steerable wire 134.

The stent crimping mechanism 6 of the present invention effectively reduces the size of prosthetic valves from 30 mm (Dmax) to 6 mm (Dmin). Prosthetic heart valve sizes typically range from about 20 mm to about 30 mm. The minimum reduction in size is therefore about 14 mm and the maximum about 24 mm. In contrast, typical coronary stents have an expanded diameter of about 3 - 6 mm and are crimped to a minimum diameter of about 1.5 - 2 mm, with a total maximum size reduction of about 4 mm. To be distinguished from conventional stent crimpers, the present invention provides a diameter reduction of at least 10 mm. In the exemplary embodiment, radial displacement of the jaws is limited by the linear spacing between the sliding elements 17 and the associated flanges 18 and slots 15, 16. Because the diametrically opposed jaws act toward each other to reduce the size of the prosthetic valves, each one pinches the valve half the distance of the full diameter reduction. Therefore, the minimum length of the slits 15, 16 is 5 mm, although the practical restriction is the freedom of movement of the sliding elements and the tabs 17 and 18 within the slots 15, 16, which is at least 5 mm.

The mechanical advantage of the crimping mechanism 6 can best be illustrated by the amount of handle rotation required to crimp a prosthetic heart valve. Specifically, the exemplary embodiment shows handle rotation of approximately 270° which results in a maximum reduction of the prosthetic valve of approximately 24 mm. At the same time, each of the 12 jaws used to crimp the prosthetic valve translates linearly without any intermediate connection between the primary motion rotating plates 3 and the jaws. The lightweight, inexpensive components contribute to ease of use and ease of removal.

In an advantageous feature, the shirring device may be formed from a plastic material to reduce cost and weight. Furthermore, due to the efficiency of the construction, the shirring mechanism may be manufactured at a relatively low cost. Accordingly, the shirring mechanism described herein is well suited for single-use purposes, thus obviating the need for sterilization between uses.

It should be noted that the particular mechanism for crimping prosthetic valves disclosed herein may be structurally modified in a number of ways while still performing its essential function. For example, in the exemplary embodiment, the jaws move radially, but are laterally or rotationally restrained. Cam elements in the jaws move along radial channels in a stationary plate, while a rotating plate with a spiral cam track provides the driving force. In a reverse configuration, the jaws may rotate while the spiral cam tracks remain stationary. The radial channels would also have to rotate with the jaws and cam elements. However, the exemplary embodiment is preferred due to the added complexity to the design with the rotating jaws. The alternative is mentioned herein only to illustrate that structural variations are entirely possible and are potentially within the scope of the claims.

Exemplary embodiments of the invention have been described, but the invention is not limited to these embodiments. Various modifications may be made within the scope without departing from the spirit and scope of the invention as set forth in the appended claims, description of the invention and accompanying drawings.

Claims (15)

1. A disposable portable shirring system (104) for prosthetic valves (120), comprising: a base (114); a valve crimper (106) mounted on the base (114) having a housing (2) and a plurality of jaws (1) radially movable within the housing (2), each jaw (1) defining an inner end having a partial crimping surface that combines with it on the other jaws (1) to form a crimping opening (50) of variable diameter and having an axial dimension sufficient to crimp an expandable prosthetic valve (120); an actuator (5) limited by stops that simultaneously moves the jaws (1) inward to reduce the opening diameter by at least 10 mm to crimp an expandable prosthetic valve (120) located within the opening (50) and subsequently, outward to release the valve (120) after crimping; and a stop mechanism that prevents the surgeon from excessively crimping the prosthetic valve (120) by mistake, characterized in that the stop mechanism comprises a set of stop elements (108) of different sizes for valves of different sizes, wherein the stop elements (108) of different sizes are separable from the valve crimper (106). 2. System (104) according to claim 1, further comprising: a support frame meter (112) mounted on the base (114) having a tapered through hole with a minimum diameter equal to the minimum opening (50) limited by the stop; and a balloon sizer (110) mounted on the base (114) having a through hole with a diameter sized to calibrate an expandable balloon therewith to a maximum diameter sufficient to expand a prosthetic valve (120). 3. System (104) according to any one of claims 1 or 2, wherein the partial gathering surface at the inner end of each jaw (1) ends at a point (100) which is located on a radius, the combination of all the partial gathering surfaces defining the opening (50), and wherein each jaw (1) moves linearly along a line, the point (100) remaining on the radius and the partial gathering surface not rotating. 4. A system (104) according to any one of claims 1 or 3, wherein each jaw (1) comprises an outer head portion (57) and an inner generally circumferentially oriented finger (52) with a recess (58) defined therebetween, and wherein each jaw (1) nests within the recess (58) of an adjacent jaw (1) and the partial gathering surface is defined on a radially innermost face of the finger (52). 5. The system (104) of claim 4, wherein the radial inner end of one jaw (1) nests within the recess (58) of an adjacent jaw (1) such that the fingers (52) of each jaw (1) overlap in the opening (50). 6. System (104) according to any of claims 1 to 5, wherein the circumferential width of each jaw (1) is substantially the same from its outer end to its inner end. 7. System (104) according to any of claims 1 to 6, wherein the number of jaws (1) is between 8 and 12. 8. System (104) according to claim 7, wherein there are twelve jaws (1), and wherein outer faces (55) of fingers (57) of each jaw (1) are straight and the opening (50) describes a dodecagon. 9. System (104) according to any of claims 1 to 8, wherein each jaw (1) is formed in a single piece. 10. System (104) according to any one of claims 1 to 9, wherein the valve gatherer (106) is formed of a plastic material. 11. System (104) according to any one of claims 1 to 10, wherein one stop element (108) of the set of stop elements (108) of different sizes is closely fitted within an opening formed in the housing (2). 12. System according to any of claims 1 to 11, wherein the stop elements (108) of the set of stop elements (108) of different size are formed in a color different from the valve ruffle. 13. The system of any one of claims 2 to 12, wherein the support frame sizer (112) and the balloon sizer (110) are formed in a different color from the valve ruffle. 14. System according to any one of claims 2 to 12, wherein the support frame meter (112) and the balloon meter (110) are removably mounted on the base (114). 15. Set comprising: the shirring system according to any one of claims 1 to 14; a balloon-expandable prosthetic heart valve (120); and a balloon catheter.